When there is a co-existing GSM RAN,
excess traffic in a WCDMA cell may be offloaded to GSM
If a call is chosen for Directed Retry
to GSM, the request for the speech RAB will be rejected with cause
"Directed retry" and then a request is made to the core network to
relocate the UE to a specific GSM cell, using the Inter-RAT handover procedure.
This handover is a blind one since the target cell is chosen not based on UE measurements.
Therefore, the target cell must be co-located with the WCDMA cell. Co-located
GSM cells are assumed to have similar coverage and accessibility as their
respective WCDMA cells.